The present invention relates to a contact probe and a socket to be used for inspecting a device to be inspected such as a semiconductor integrated circuit.
In case of inspecting an object to be inspected such as a semiconductor integrated circuit, contact probes are generally used for electrically connecting the object to be inspected to an inspecting board at a side of a measuring instrument.
FIG. 17(A) is a sectional front view of a socket 900 in which related-art contact probes 800 are supported by an insulating support body 831 in a state of standby (in a state where springs are released), and FIG. 17(B) is a sectional front view of the same in a state where Kelvin measurement is carried out (in a state where the springs are contracted). It is to be noted that in the drawings, first plungers 801 and second plungers 802 of the respective contact probes 800 are not shown in section.
The socket 900 which is shown in the drawings is to be used for Kelvin measurement. The Kelvin measurement is a method for measuring electrical performance by bringing a current supplying probe and a voltage monitoring probe into contact with an electrode of an object 5 to be inspected, for example, an electrode bump 5a (Reference should be made to JP-A-2008-45986, according to necessity). In the socket 900, one of the two contact probes 800 having the mutually same structure is used as the current supplying probe, and the other is used as the voltage monitoring probe.
Each of the contact probes 800 is provided with the first plunger 801, the second plunger 802, a spring 803, and a tube 804. The first plunger 801 is a component to be connected to the object 5 to be inspected, and the second plunger 802 is a component to be connected to an inspection board 6 (adapted to be connected to a measuring instrument, which is not shown). A flange part 812 of the first plunger 801 in a shape of a disc having a larger diameter than a distal end side columnar part 824 is provided for preventing withdrawal of the contact probe 800 in a state as shown in FIG. 17(A), and for aligning a projecting length of the distal end side columnar part 824. A distal end face of the distal end side columnar part 824 is split into angled shapes (herein, split in eight), and there are eight apexes of the angled shapes along an outer circumference, at an equal angle from the center.
In the contact probe 800 as shown in FIGS. 17(A) and 17(B), the flange part 812 protrudes toward the adjacent contact probe 800, and therefore, the two adjacent contact probes 800 are unable to be disposed in a manner that their distal end side columnar parts 824 may stand close to each other. Accordingly, a contact pitch, which will be described below, cannot be made smaller.
FIG. 18(A) is a view as seen from a direction of arrow marks A-A′ in FIG. 17(B). FIG. 18(B) is a sectional view taken along a line B-B′ in FIG. 17(B). FIG. 19 is an enlarged view of a region surrounding distal end parts of the first plungers 801 in FIGS. 17(A) and 17(B). Referring to these drawings, a contact pitch P1 between the adjacent contact probes 800 will be described.
The contact pitch P1 is represented by the following equation.P1=E+(F×2)+(G×2)+(H×2)  Equation 1
E: the smallest wall thickness of the insulating support body 831
F: a gap between the insulating support body 831 and a side face of the flange part 812
G: a difference in radius between the flange part 812 and the distal end side columnar part 824
H: a distance from a side face of the distal end side columnar part 824 (the side face which is the closest to the adjacent columnar part 824) to the apex of the angled shape of the distal end face. This distance is a distance measured along a direction interconnecting the adjacent contact probes 800. Although this distance may be zero, in some cases, depending on a rotation angle of the distal end side columnar part 824, the distance is herein deemed as the largest distance (in a state of FIG. 18(A)).
As describe above, protrusion of the flange part 812 directly affects the contact pitch P1, and makes it difficult to achieve the smaller contact pitch. It is to be noted that the lengths E and F out of the aforesaid lengths E to H are unable to be made zero for designing reason.